1. Technical Field
The present invention concerns a charging apparatus for charging electric storage devices of electric vehicles. The present invention further concerns a wind power installation and also an electric filling station as well as the use of a feed-in unit of a wind power installation and a method of controlling a charging apparatus connected to an ac voltage network.
2. Description of the Related Art
Electric vehicles are becoming increasingly important because of the present worldwide energy shortage of fossil fuels and also the known poor efficiency of spark-ignition engines and even diesel engines. In that respect, the term electric vehicle is used to denote in particular a passenger car powered by one or more electric motors. That can also include hybrid vehicles which can be powered not only by an electric motor but which additionally have another engine such as internal combustion engine.
Such electric vehicles frequently store their energy in electric storage devices, also called batteries. In accordance with the present invention and the description hereinafter the terms electric storage device, accumulator, battery, and accu battery are used to denote any electric storage device which can store the electric power that can be supplied to one or more electric drive motors of an electric vehicle. An electric vehicle includes any vehicle that moves under electric power and includes in particular an electric car. The storage capacities of such electric storage devices can be for example 30 to 50 kWh, and are typically 35 kWh.
An electric storage device is also referred to herein by the term accumulator or for brevity an accu battery. Thus the terms electric storage device and battery are intended to be used in the broad sense of any device that will store electricity and not just chemical types.
In particular a distinction can be made between two general concepts for charging such electric storage devices. In accordance with one concept the electric storage devices are charged directly on the car, in which case the electric storage device remains on the car or other electric vehicle while it is being charged. Another concept proposes replacing an entirely or partially discharged electric storage device by a charged one. In this second concept the electric vehicle needing more power therefore goes to a location at which at least one electric storage device of the same structure is provided in the charged condition and the entirely or partially discharged electric storage device is replaced by the fully charged and ready to use electric storage device. The entirely or partially remaining electric storage device can then be charged up while the electric vehicle can continue to be driven. The second concept has the benefit of being much faster to provide a fully charged electric storage device to an electric vehicle so it can continue to be driven.
Such an electric storage device replacement operation can be provided preferably at a central location such as an electric filling station. Therefore the term electric filling station is used to denote any location at which an electric vehicle can receive electric power, either by charging or replacement of the electric storage device. To ensure good availability such an electric filling station must have a large number of electric storage devices in stock. If it is assumed for example that there are 50 electric storage devices in stock which have to be charged up, with a charging power requirement of 50 to 100 kW per electric storage device, that electric filling station in this example must have a charging power of 2.5 to 5 MW. Such a charging power makes high demands not only on the charging apparatus as such but also on the link to an electric supply network or to a corresponding branch of the electric supply network which leads to the aforementioned electric filling station, and to the aforementioned charging apparatus.
In that respect it is to be noted that, upon an increase that is to be expected in the number of electric vehicles, it is necessary to plan for not only on an electric filling station but a plurality of and optimally a large number of electric filling stations which are distributed to cover a large area. The aim would be to provide such a situation for the electric vehicle users so they can be assured of always having the ability to have sufficient electric power to drive their electric vehicle.
As general state of the art, attention is directed to the following documents: DE 103 31 084 A1, WO 2005/008808 A2, U.S. Pat. No. 2006/0192435 A1 and DE 100 08 028 A1 and a publication by Dirk Uwe Sauer, “Elektrische Energiespeicher in Hybrid-und Elektrofarhzeugen”, Seminar für Kraftfahrzeug-und Motorentechnik Berlin, Jan. 29, 2009.